What is prohibited in relation to the waste stack between fixture drain connections?

Having both horizontal and vertical offsets in relation to the waste stack between fixture drain connections is prohibited due to concerns about proper drainage and preventing the possibility of blockages or sewage backup. Horizontal offsets can create challenges for sewage flow, potentially leading to accumulation of waste. Vertical offsets may disrupt the gravitational pull necessary for efficient drainage, leading to similar issues.

The International Residential Code emphasizes maintaining a straightforward flow in the waste stack to ensure that solids and liquids can move freely without hindrances. This ensures that the plumbing system operates effectively and minimizes the risk of clogs or overflows that can occur if waste flow is impeded by unnecessary angles or changes in direction. Therefore, prohibiting both types of offsets helps maintain the integrity and functionality of the drainage system.